The present invention relates to an elongated building element, preferably one having a tongue and groove. A conventional building element is of thick gauge mostly solid material and is thus too heavy, to be earned by one person alone. Such building elements are used for constructing outer and inner walls, roofs, and also floors. Grooves and tongues are arranged to cooperate to ensure a coherent surface when the elements are fitted together. It is also possible to build walls out of logs dovetailed at the corners, in which case each building element, besides having tongues and grooves, will be provided with a transverse recess with a width corresponding to the thickness of the element and a depth generally half the height of the element. Instead of tongues and grooves, a pole may be passed through building elements stacked one on top of the other in order to hold them together.